JP2607440Y2 - Pyroelectric sensor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric sensor used for infrared detection.

[0002]

2. Description of the Related Art A general conventional pyroelectric sensor used for the above purpose has a gate resistor 21 and an FE as shown in FIG.
The mounting component of T22 is attached to the alumina substrate 23, and the light receiving electrode 25 of the pyroelectric element 24 and each mounting component are electrically connected by the lead terminal 26, and the pyroelectric element 24 and the alumina substrate 23 are supported by the lead terminal 26. In most cases, it is housed in the case 27.

The reason why the alumina substrate 23 is used for mounting the gate resistor 21 and the FET 22 is that it is considered that these components cannot be directly mounted on the pyroelectric element 24 due to the limitation of the strength of the pyroelectric element 24. However, the above structure requires a space for installing the alumina substrate 23 in the case 27, which limits the miniaturization of the sensor and requires a troublesome circuit pattern for wiring connection between components.

An example in which components are directly mounted on the pyroelectric element 31 is, for example, Japanese Utility Model Laid-Open No. 3-72828. In this prior example, as shown in FIG. 7, the specific resistance of the pyroelectric element 31 is used for the gate resistance, and only the chip FET 32 is electrically connected to the electrode pattern formed on the pyroelectric element 31 as a mounting component. The electrode pattern is directly conductively connected to the lead terminal 33 while supporting the pyroelectric element 31.

[0005]

With the above structure, an alumina substrate is not required, and the size of the sensor can be reduced. In addition, since the specific resistance of the pyroelectric element 31 is used as the gate resistance, it is not necessary to separately mount a resistor, which is effective in reducing the weight burden on the pyroelectric element 31. When the pyroelectric sensor characteristics are arbitrarily changed, it is not possible to respond by changing the resistance value, and the pyroelectric element itself needs to be replaced. Several types of pyroelectric elements having different resistance values must be prepared in advance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pyroelectric sensor having a structure capable of contributing to stable support of a pyroelectric element without mounting weight on the pyroelectric element by mounting a resistance element.

In order to achieve the above object, a pyroelectric sensor according to the present invention has a pyroelectric element, an FET, and a resistive element, and has three lead terminals mounted on the stem and mounted on the stem. A pyroelectric sensor which supports the pyroelectric element by four-point support with a resistance element and is housed in a case,
The pyroelectric element is a ceramic plate-like body that generates electric charges by inputting infrared rays.
A drain / source / gate connection electrode of the ET and an installation electrode are provided, and the FET is used for impedance conversion, and is connected to the drain / source / gate connection electrode of the FET and mounted on the back surface of the pyroelectric element. The drain-source-gate connection electrode of the FET has three lead ends.
The lead terminal connected to one of the terminals and connected to the ground electrode is a ground lead terminal, and the resistance element is
The gate resistance, and the rising height of each lead terminal
It has a columnar shape of the same length, and is electrically connected to the gate connecting electrode of the FET and the ground lead terminal through the stem ,
An upright posture on the stem without putting weight on the pyroelectric element
It is bonded.

[0008]

The pyroelectric element is stably supported on the stem by three lead terminals for power supply and ground, and a resistance element. The resistance element is electrically connected to the gate connection electrode of the FET and the ground lead terminal, and functions as a gate resistance. A commercially available columnar resistor can be used as the resistance element, and the mounting of the resistance element does not place a heavy burden on the pyroelectric element, and the change in the pyroelectric sensor characteristics can be handled by replacing the resistance element.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
In FIG. 1, a pyroelectric element 1 built in the pyroelectric sensor of the present invention is shown.
, A column-shaped resistance element 4 is mounted on a stem 3, and four corners of the pyroelectric element 1 are supported by the resistance element 4 and three lead terminals 5 protruding above the stem 3. , And hermetically sealed by the shield case 6. An optical filter 7 is provided on the infrared receiving window on the upper surface of the shield case 6.

The pyroelectric element 1 is a ceramic plate that generates electric charges by inputting infrared rays. In the embodiment, a square chip is used.

2A and 2B, the pyroelectric element 1
The power receiving electrode 8 on the front surface, the ground electrode 9 on the back surface,
T drain / source / gate connection electrodes 10a, 10
b, 10c.

In FIG. 3 (a), the drain of the FET
A conductive adhesive is applied to the location of the source-gate connection electrodes 10a, 10b, and 10c at a position A indicated by ●, as shown in FIG.
The FET 2 is connected across the electrodes as shown in FIG. The position B indicated by a circle in the figure is the connection position of the lead terminal.

In FIG. 4 (a), on the stem 3, 3 corresponding to the B position of the ground electrode 9 of the pyroelectric element 1 and the B-position of the drain-source connection electrodes 10a, 10b of the FET, respectively.
Two lead terminals 5 are provided. That is, three
The lead terminals 5 are connected to the ground electrode 9 and the drain connection, respectively.
Electrode 10a and the source connection electrode 10b are individually connected.
The pyroelectric element 1 is supported on three lead terminals 5.
It is. The lead terminal connected to the grounding electrode 9 is for grounding
It is a lead terminal. In merits further conductive adhesive is applied to the position A on the stem 3, bonding the resistive element 4 of the columnar rise height and the length of each lead terminal 5 in an upright position as shown in FIG. 4 (b) , Conductive contact
The adhesive is connected to the gate electrode 10c of the FET. The resistance element 4 is a gate resistance of the FET, and is electrically connected to the ground lead terminal 5 through the stem 3.
Reference numeral 1 denotes three lead terminals 5, 5, 5 and one resistor element 4.
And four-point support.

Next, a conductive adhesive is applied to each lead terminal 5 and the top C of the resistance element 4 and the pyroelectric element 1 is bonded.
Baking is performed, and the pyroelectric element 1 is supported and fixed to the lead terminal 5 and the resistance element 4 as shown in FIG. After that, the case 11 is put on the pyroelectric element 1 and superposed on the stem 3, and the joint is welded and sealed as shown in FIG.
Is completed. As described above, the conductive adhesive is used for bonding the elements in the embodiment, but it is needless to say that the bonding can be performed using solder.

[0015]

According to the present invention, as described above, a columnar resistor is used for the gate resistor used in the pyroelectric element, and three lead terminals for connecting the drain, source, and gate of the FET and for grounding, and the resistor are used. Because the pyroelectric element is supported on the stem by the above, the pyroelectric element can be stably supported by the four-point support, and the weight load of the resistance element is not applied to the pyroelectric element. Further, since the contact area between the pyroelectric element and the resistance element is small, a decrease in heat conduction is small, and a decrease in the reaction speed to infrared rays can be prevented.

Further, if the length of each lead terminal projecting from the stem and the length of the resistance element are shortened and the FET mounted on the pyroelectric element is supported on the stem, the stability of the support of the pyroelectric element is improved. Can be further improved.

Further, a commercially available columnar resistance element can be used as the resistance element, and there is an effect that a change in pyroelectric sensor characteristics can be dealt with by replacing the resistance element.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pyroelectric sensor showing one embodiment of the present invention.

FIG. 2A is a front view of a pyroelectric element, and FIG. 2B is a rear view.

FIG. 3A is a diagram showing a mounting position of an FET on a back surface of a pyroelectric element, and FIG. 3B is a diagram showing a mounting position of a FET and a mounting position of a lead terminal.

FIG. 4A is a view showing a procedure for mounting a resistance element, and FIG. 4B is a view showing a procedure for mounting a pyroelectric element.

FIG. 5A is a diagram showing a sealing procedure, and FIG. 5B is a diagram showing a sealed pyroelectric sensor.

FIG. 6 is a conventional example of a pyroelectric sensor.

FIG. 7 is another conventional example of a pyroelectric sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pyroelectric element 2 FET 3 Stem 4 Resistance element 5 Lead terminal 6 Shield case 7 Optical filter 8 Power receiving electrode 9 Ground electrode 10a, 10b, 10c Drain source of FET
Gate connection electrode 11 case

Continuing on the front page (72) Inventor Tomohiro Yamamura 3158, Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama Prefecture Inside Hokuriku Electric Industry Co., Ltd. (56) References JP-A-3-4127 (JP, A) JP-A-2-72944 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01J 1 / 02 G01J 1/42 G01J 5/02 G01J 5/12 G01V 9/04 H01L 37/00-37/02 G08B 13/19-13/191

Claims (1)

(57) [Scope of request for utility model registration] 1. A pyroelectric element comprising a pyroelectric element, an FET, and a resistance element, wherein the pyroelectric element is supported by four points of three lead terminals attached to the stem and a resistance element attached to the stem. A pyroelectric sensor housed in a case, wherein the pyroelectric element is a ceramic plate-like body that generates an electric charge by inputting infrared rays, and has a light receiving electrode on the front surface and an F electrode on the back surface.
A drain / source / gate connection electrode of the ET and an installation electrode are attached. The FET is for impedance conversion, and is connected to the drain / source / gate connection electrode of the FET and mounted on the back surface of the pyroelectric element. The drain-source-gate connection electrode of the FET is
Are connected to one of the three lead terminals, the lead terminal connected to the ground electrode is a grounding lead terminals, the resistor element is the gate resistance, the falling of the lead terminals
It has a pillar shape with the same height as the rising height, and is electrically connected to the gate connecting electrode of the FET and the grounding lead terminal through the stem , so that the pyroelectric element is placed on the stem without burdening the weight.
A pyroelectric sensor, wherein the pyroelectric sensor is adhered to an erect posture .